Conventional engines need a transmission to obtain output power. In order to simplify the complicated structure of the engine, the invented transmission mechanism can use the two-times satisfaction of Newton' Third Law in the double-rotor rotary engine end turbine to adjust the output power relative to the speed of engine, which is caused by a velocity-pressure change of the combustion products passing through the turbine of the engine.
The double-rotor rotary engine and turbine, which was patented in U.S. Pat. No. 4,912,923, has the most important feature that the output power is produced by two-times satisfaction of Newton's Third Law in each explosion stroke. This feature can be caused by the combustion products to move the piston relative to the cylinder and also to make the turbine produce a tangential-force on the rotatable housing which, in turn, takes the role of base to react on the shaft of the engine. Hence, the speed of the engine is in response to the torque reaction between the rotatable housing and the base of the engine as produced by the exhaust turbine, and between the rotatable housing and the shaft of the engine as produced by the expansion of combustion products in the cylinder.
Therefore, the invented transmission mechanism uses said features of the engine to change the speed and pressure of combustion products passing through the turbine for adjusting the output power relative to the speed of the engine without the transmission of conventional engines.